Academic literature on the topic 'Foliar fungal pathogens'
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Journal articles on the topic "Foliar fungal pathogens"
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Çelik Oğuz, Arzu, and Aziz Karakaya. "Genetic Diversity of Barley Foliar Fungal Pathogens." Agronomy 11, no. 3 (February 27, 2021): 434. http://dx.doi.org/10.3390/agronomy11030434.
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Powdery mildew, net blotch, scald, spot blotch, barley stripe, and leaf rust are important foliar fungal pathogens of barley. Fungal leaf pathogens negatively affect the yield and quality in barley plant. Virulence changes, which can occur in various ways, may render resistant plants to susceptible ones. Factors such as mutation, population size and random genetic drift, gene and genotype flow, reproduction and mating systems, selection imposed by major gene resistance, and quantitative resistance can affect the genetic diversity of the pathogenic fungi. The use of fungicide or disease-resistant barley genotypes is an effective method of disease control. However, the evolutionary potential of pathogens poses a risk to overcome resistance genes in the plant and to neutralize fungicide applications. Factors affecting the genetic diversity of the pathogen fungus may lead to the emergence of more virulent new pathotypes in the population. Understanding the factors affecting pathogen evolution, monitoring pathogen biology, and genetic diversity will help to develop effective control strategies.
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Allan, Eric, Jasper van Ruijven, and Michael J. Crawley. "Foliar fungal pathogens and grassland biodiversity." Ecology 91, no. 9 (September 2010): 2572–82. http://dx.doi.org/10.1890/09-0859.1.
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Fang, Kai, Jie Zhou, Lin Chen, Yu-Xuan Li, Ai-Ling Yang, Xing-Fan Dong, and Han-Bo Zhang. "Virulence and community dynamics of fungal species with vertical and horizontal transmission on a plant with multiple infections." PLOS Pathogens 17, no. 7 (July 15, 2021): e1009769. http://dx.doi.org/10.1371/journal.ppat.1009769.
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The virulence evolution of multiple infections of parasites from the same species has been modeled widely in evolution theory. However, experimental studies on this topic remain scarce, particularly regarding multiple infections by different parasite species. Here, we characterized the virulence and community dynamics of fungal pathogens on the invasive plant Ageratina adenophora to verify the predictions made by the model. We observed that A. adenophora was highly susceptible to diverse foliar pathogens with mixed vertical and horizontal transmission within leaf spots. The transmission mode mainly determined the pathogen community structure at the leaf spot level. Over time, the pathogen community within a leaf spot showed decreased Shannon diversity; moreover, the vertically transmitted pathogens exhibited decreased virulence to the host A. adenophora, but the horizontally transmitted pathogens exhibited increased virulence to the host. Our results demonstrate that the predictions of classical models for the virulence evolution of multiple infections are still valid in a complex realistic environment and highlight the impact of transmission mode on disease epidemics of foliar fungal pathogens. We also propose that seedborne fungi play an important role in structuring the foliar pathogen community from multiple infections within a leaf spot.
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Brown, Alexander, and Robert W. Heckman. "Light alters the impacts of nitrogen and foliar pathogens on the performance of early successional tree seedlings." PeerJ 9 (July 8, 2021): e11587. http://dx.doi.org/10.7717/peerj.11587.
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Light limitation is a major driver of succession and an important determinant of the performance of shade-intolerant tree seedlings. Shade intolerance may result from a resource allocation strategy characterized by rapid growth and high metabolic costs, which may make shade-intolerant species particularly sensitive to nutrient limitation and pathogen pressure. In this study, we evaluated the degree to which nitrogen availability and fungal pathogen pressure interact to influence plant performance across different light environments. To test this, we manipulated nitrogen availability (high, low) and access by foliar fungal pathogens (sprayed with fungicide, unsprayed) to seedlings of the shade-intolerant tree, Liquidambar styraciflua, growing at low and high light availability, from forest understory to adjacent old field. Foliar fungal damage varied with light and nitrogen availability; in low light, increasing nitrogen availability tripled foliar damage, suggesting that increased nutrient availability in low light makes plants more susceptible to disease. Despite higher foliar damage under low light, spraying fungicide to exclude pathogens promoted 14% greater plant height only under high light conditions. Thus, although nitrogen availability and pathogen pressure each influenced aspects of plant performance, these effects were context dependent and overwhelmed by light limitation. This suggests that failure of shade-intolerant species to invade closed-canopy forest can be explained by light limitation alone.
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van Esse, H. Peter, Emilie F. Fradin, Philip J. de Groot, Pierre J. G. M. de Wit, and Bart P. H. J. Thomma. "Tomato Transcriptional Responses to a Foliar and a Vascular Fungal Pathogen Are Distinct." Molecular Plant-Microbe Interactions® 22, no. 3 (March 2009): 245–58. http://dx.doi.org/10.1094/mpmi-22-3-0245.
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Plant activation of host defense against pathogenic microbes requires significant host transcriptional reprogramming. In this study, we compared transcriptional changes in tomato during compatible and incompatible interactions with the foliar fungal pathogen Cladosporium fulvum and the vascular fungal pathogen Verticillium dahliae. Although both pathogens colonize different host tissues, they display distinct commonalities in their infection strategy; both pathogens penetrate natural openings and grow strictly extracellular. Furthermore, resistance against both pathogens is conveyed by the same class of resistance proteins, the receptor-like proteins. For each individual pathogen, the expression profile of the compatible and incompatible interaction largely overlaps. However, when comparing between the two pathogens, the C. fulvum-induced transcriptional changes show little overlap with those induced by V. dahliae. Moreover, within the subset of genes that are regulated by both pathogens, many genes show inverse regulation. With pathway reconstruction, networks of tomato genes implicated in photorespiration, hypoxia, and glycoxylate metabolism were identified that are repressed upon infection with C. fulvum and induced by V. dahliae. Similarly, auxin signaling is differentially affected by the two pathogens. Thus, differentially regulated pathways were identified with novel strategies that allowed the use of state-of-the-art tools, even though tomato is not a genetic model organism.
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Akanmu, Akinlolu Olalekan, Timothy Oladiran Ajiboye, Masego Seleke, Sabelo D. Mhlanga, Damian C. Onwudiwe, and Olubukola Oluranti Babalola. "The Potency of Graphitic Carbon Nitride (gC3N4) and Bismuth Sulphide Nanoparticles (Bi2S3) in the Management of Foliar Fungal Pathogens of Maize." Applied Sciences 13, no. 6 (March 15, 2023): 3731. http://dx.doi.org/10.3390/app13063731.
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Maize (Zea mays L.) is the most significant grain crop in South Africa. Despite its importance, the cereal is ravaged by several foliar fungal pathogens, which reduce maize quality and quantity at harvest. Hence, this study investigates the fungi associated with foliar diseases of maize in Molelwane, North-West Province, South Africa. The fungi were isolated, characterized and subjected to in vitro nanoparticle control. Samples of diseased maize leaves were aseptically collected from two maize-growing farms. Fungi associated with the samples were isolated and characterized using standard procedures. Bi2S3 (metal-containing) and gC3N4 (non-metallic carbon-based) nanoparticles were synthesized and used to challenge the pathogens using standard procedures. Foliar fungal pathogens isolated from the diseased maize leaves in this study were characterized as Bipolaris zeicola, Phoma herbarum, Epicoccum nigrum, Alternaria alternata and Fusarium brachygibbosum. Phoma herbarium > A. alternata > B. zeicola > F. brachygibbosum > E. nigrum was the order of percentage fungal inhibition by the nanoparticles. Bi2S3 was more effective against the pathogens at lower concentrations and gC3N4 at higher concentration levels. The two nanoparticle types evaluated in vitro shows potential for managing the foliar fungal pathogens, and this needs to be further validated in field studies.
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Barbetti, M. J., and M. P. You. "Opportunities and challenges for improved management of foliar pathogens in annual clover pastures across southern Australia." Crop and Pasture Science 65, no. 12 (2014): 1249. http://dx.doi.org/10.1071/cp14117.
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Foliar pathogens result in significant losses in herbage and seed yields and regeneration capacity in annual clover pastures, the last leading to their rapid deterioration and lack of persistence. The most important pathogens include Kabatiella caulivora (clover scorch), Cercospora zebrina (cercospora), Uromyces trifolii-repentis (rust), Erysiphe trifoliorum (powdery mildew), and Leptosphaerulina trifolii (pepper spot). Several other foliar pathogens on annual clovers, in particular Phoma medicaginis (black stem and leaf spot), one or more Stemphylium spp. (stemphylium leaf spot), Pseudopeziza trifolii (common leaf spot), Stagonospora spp. (stagonospora leaf spot), Colletotrichum trifolii (anthracnose) and Sclerotinia trifoliorum (sclerotinia), occur widely and together contribute to reduce productivity in some localities. Severe attack by the most important pathogens (e.g. K. caulivora, U. trifolii-repentis, E. trifoliorum) not only greatly reduces winter–spring pasture production but frequently also coincides with the critical feed shortage across autumn–winter, leading to significantly decreased autumn–winter biomass production in regenerating stands. Approaches to disease control include a range of management strategies. Wider utilisation of cultural and fungicidal control strategies offers producers greater management flexibility, particularly in conjunction with deployment of cultivars with useful resistance. Host resistance offers the greatest potential for delivering the most cost-effective and long-term control. Many of these foliar pathogens co-occur, magnifying losses; this highlights the need for individual host genotypes with resistance to multiple pathogens and unique geographic locations such as Sardinia offer enormous scope to select such clovers. Future research opportunities and critical priorities to improve management of foliar pathogens in annual clover pastures across southern Australia include the need to: (i) define pathogen strain–race structures, particularly for K. caulivora and U. trifolii-repentis, and determine associated host resistances against specific strains–races to allow strategic deployment of host resistances; (ii) define relative resistances to major fungal foliar pathogens of all parental and near-release breeding genotypes and all commercial cultivars across important annual clover species; (iii) identify new sources of host resistance, particularly genotypes with cross-resistance to multiple pathogens, for breeders to utilise; (iv) identify and demonstrate the benefits to farmers of effective cultural (e.g. grazing, removal of infested residues) and fungicidal control options that allow greater management flexibility to reduce the impact of fungal foliar diseases; and (v) determine current incidences and impacts (losses and economic importance) of major fungal foliar diseases in the different agro-climatic regions across southern Australia. Failure to address these critical issues leaves livestock industries carrying the risks from release of new varieties of unknown susceptibilities to one or more of the major foliar diseases, and the risks from continued use of older varieties exposed to new pathogen races; with few if any flexible management options during periods of critical feed shortage; and without the basic information on current disease impacts that is needed to make sensible management and funding decisions.
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Dawadi, Sujan, Fulya Baysal-Gurel, Karla M. Addesso, Prabha Liyanapathiranage, and Terri Simmons. "Fire Ant Venom Alkaloids: Possible Control Measure for Soilborne and Foliar Plant Pathogens." Pathogens 10, no. 6 (May 27, 2021): 659. http://dx.doi.org/10.3390/pathogens10060659.
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The purpose of this study was to evaluate fire ant venom alkaloids and an alarm pheromone analog against several plant pathogens, including Botrytis cinerea, Fusarium oxysporum, Phytophthora nicotianae, P. cryptogea, Pseudomonas syringae, Phytopythium citrinum, Rhizoctonia solani, Sclerotonia rolfsii, Xanthomonas axonopodis, and X. campestris. All pathogens were tested against red imported fire ant venom alkaloid extract and alarm pheromone compound for growth inhibition in in vitro assay. The venom alkaloid extract inhibited fungal and oomycete pathogens. Neither of the treatments were effective against bacterial pathogens. Three soilborne pathogens, P. nicotianae, R. solani, F. oxysporum, and one foliar pathogen, B. cinerea were selected for further in-vivo assays on impatiens (Impatiens walleriana ‘Super Elfin XP violet’). Total plant and root weight were higher in venom alkaloid treated plants compared to an inoculated control. The venom alkaloid treatment reduced damping-off, root rot severity, and pathogen recovery in soilborne pathogen inoculated plants. Similarly, venom alkaloid reduced Botrytis blight. However, higher venom rates caused foliar phytotoxicity on plants. Therefore, additional work is needed to evaluate rates of venom alkaloids or formulations to eliminate negative impacts on plants. Overall, these results suggest that red imported fire ant venom alkaloids may provide a basis for new products to control soilborne and foliar plant pathogens.
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Tomoshevich, M. A., D. Belomesyatseva, E. V. Banaev, I. G. Vorob’eva, and T. Shabashova. "Comparative Analysis of Foliar Diseases of Some Native and Non-Native Tree Species in Belarus and Siberia." Contemporary Problems of Ecology 16, no. 2 (April 2023): 217–29. http://dx.doi.org/10.1134/s1995425523020166.
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Abstract Urban green spaces are known to be subjected to additional anthropogenic stress. Using native plants in monoculture, i.e., planting trees of the same species, may favour disease outbreaks and plant death. Non-native plants to be used in large cities for creating sustainable plantations are being searched for worldwide. Meanwhile, it is necessary to control plant pathogens in the variable conditions of the region and natural habitat. In Siberian cities, non-native European trees are used, and non-native Siberian plants are introduced in Belarus. This article reports long-term observations of foliar fungal pathogens attacking 21 woody plants (19 European, 2 Siberian) in Siberian and Belarusian cities. In both regions, 48 leaf fungal pathogens were detected, with powdery mildew fungi predominating in Belarus and leaf spotting fungi prevailing in Siberia. In both research regions, the greatest number of fungal species was found on Syringa vulgaris L. In Siberia, many pathogens were found on the non-native European plant Berberis vulgaris (9 species) and native plant Caragana arborescens Lam. (8 species). We have not detected the pathogens on European plants: Acer campestre L., Acer platanoides L., Euonymus europaeus L., Lonicera caprifolium L. in urban green areas in Siberia, while we have identified one to four foliar fungal pathogens on these plants in Belarus. To sum up: more pathogens were found on native plants in Siberia and Belarus; some leaf pathogen species (Sawadaea tulasnei (Fuckel) Homma, Erysiphe alphitoides (Griffon & Maubl.) U. Braun & S. Takam., Cladosporium syringae (Oudem.) Montem., Erysiphe syringae Schwein., Erysiphe palczewskii (Jacz.) U. Braun & S. Takam.) followed their host plants (Acer tataricum L., Syringa vulgaris L., Caragana arborescens Lam.) when introduced into new areas; and some local pathogens were also observed to spread to the non-native plants of closely related species.
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Magarey, R. D., T. B. Sutton, and C. L. Thayer. "A Simple Generic Infection Model for Foliar Fungal Plant Pathogens." Phytopathology® 95, no. 1 (January 2005): 92–100. http://dx.doi.org/10.1094/phyto-95-0092.
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In this study, a simple generic infection model was developed for predicting infection periods by fungal foliar pathogens. The model is designed primarily for use in forecasting pathogens that do not have extensive epidemiological data. Most existing infection models require a background epidemiological data set, usually including laboratory estimates of infection at multiple temperature and wetness combinations. The model developed in this study can use inputs based on subjective estimates of the cardinal temperatures and the wetness duration requirement. These inputs are available for many pathogens or may be estimated from related pathogens. The model uses a temperature response function which is scaled to the minimum and optimum values of the surface wetness duration requirement. The minimum wetness duration requirement (Wmin) is the number of hours required to produce 20% disease incidence or 5% disease severity on inoculated plant parts at a given temperature. The model was validated with published data from 53 controlled laboratory studies, each with at least four combinations of temperature and wetness. Validation yielded an average correlation coefficient of 0.83 and a root mean square error of 4.9 h, but there was uncertainty about the value of the input parameters for some pathogens. The value of Wmin varied from 1 to 48 h and was relatively uniform for species in the genera Cercospora, Alternaria, and Puccinia but less so for species of Phytophthora, Venturia, and Colletotrichum. Operationally, infection models may use hourly or daily weather inputs. In the case of the former, information also is required to estimate the critical dry-period interruption value, defined as the duration of a dry period at relative humidities <95% that will result in a 50% reduction in disease compared with a continuous wetness period. Pathogens were classified into three groups based on their critical dry-period interruption value. The infection model is being used to create risk maps of exotic pests for the U.S. Department of Agriculture's Animal Plant Health and Inspection Service.
Dissertations / Theses on the topic "Foliar fungal pathogens"
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Beare, Julie Anne. "Performance of Populus trichocarpa x balsamifera and its two foliar fungal pathogens Marssonina sp. and Melampsora sp. under elevated ozone." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300051.
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Précigout, Pierre-Antoine. "Epidemiology and evolution of fungal foliar pathogens in the face of changes in crop fertilization : application of evolutionary-ecological theory to crop epidemiology." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC108/document.
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La recherche d’une agriculture durable et respectueuse de l’environnement passe par une réduction de l’usage d’intrants de synthèse. L’agroécologie cherche à utiliser les interactions entre les organismes de l’agroécosystème pour optimiser son fonctionnement, comme la régulation naturelle des bioagresseurs. C’est dans cette optique que s’inscrit ce travail de thèse qui étudie l’effet de la fertilisation des cultures sur les épidémies de pathogènes foliaires fongiques des cultures. De plus, nous étudions l’évolution des pathogènes face à des scénarios de fertilisation. Cela questionne la durabilité des pratiques culturales qui participent à la régulation les épidémies. Pour répondre à ces questions, nous avons adopté une démarche de modélisation qui permet de simuler l’effet de différents scénarios de fertilisation. Le point de départ et l’originalité de notre démarche a été de considérer le système hôte-pathogène comme un système ressource-consommateur et d’y appliquer des concepts de l'écologie évolutive pour répondre à ces questions agronomiques. Dans les deux modèles construits durant cette thèse, la fertilisation influence directement la quantité de ressources disponible pour le pathogène. Nous nous y concentrons sur un trait d'histoire de vie du pathogène, la période de latence (durée séparant l'infection du début de la sporulation), qui correspond à la durée minimale d'un cycle infectieux et qui, conditionne la stratégie d'allocation des ressources du pathogène. La latence détermine en effet la quantité de ressource qui sera allouée à la croissance du mycélium (donc sa taille à maturité) et celle qui sera ensuite allouée à la sporulation (en relation avec sa taille). Les modèles développés permettent d'étudier les réponses épidémiologique et évolutive des pathogènes foliaires fongiques à la fertilisation des cultures, avec comme référence le système Blé d'hiver/Rouille brune. Nous avons considéré différentes échelles dans ce travail : depuis la lésion où le pathogène se nourrit directement sur son hôte, jusqu’à la parcelle où se développent les épidémies et au paysage où les flux de spores entre les parcelles sont source d’extension des épidémies dans l’agroécosystème. Un premier modèle, à l'intersection des modèles épidémiologiques "SEIR" et des modèles de populations structurées, couvre les échelles de la lésion à celles de l’épidémie et de la parcelle. Le second modèle, à l'intersection des modèles SEIR et des modèles spatiaux d'épidémiologie du paysage, couvre les échelles de la parcelle au paysage agricole. Nous étudions les dynamiques épidémiologiques et évolutives, en comparant des concepts de fitness empiriques et d’invasion. Nous montrons que la fertilisation des cultures, en déterminant la dynamique des ressources disponibles pour les pathogènes, impacte fortement les épidémies. Nos modèles prédisent que la latence des pathogènes évolue en réponse à des compromis écologiques variés, d’une part pour optimiser l’allocation des ressources au niveau des feuilles, mais également pour gagner la course face à la croissance du couvert. La fertilisation, en changeant les concentrations de métabolites foliaires et les dynamiques de croissance du couvert, impacte donc épidémies et réponses évolutives de la latence des pathogènes. A l’échelle du paysage, l’introduction de pratiques variées de fertilisation dans un paysage préalablement homogène pourrait permettre de réduire les épidémies. Cependant, notre modèle prédit une durée limitée de cet effet du fait de l’évolution et de la diversification des pathogènes dans un paysage hétérogène. Ce travail ouvre la voie à des travaux sur l’effet et la durabilité des pratiques pour réguler les épidémies dans l’agroécosystème. Enfin, nous montrons par un travail de méta-analyse qu’il existe une relation forte entre type trophique et latence du pathogène, suggérant que les différents types de pathogènes répondront différemment à des scénarios de réduction de fertilisationThe quest for a sustainable agriculture requires a reduction in the use of synthetic inputs. In this perspective, agroecology seeks to use interactions between organisms in the agroecosystem to replace inputs by ecosystem services, such as the natural regulation of pests and diseases. In this context, this thesis studies the effect of crop fertilization on epidemics of crop fungal foliar pathogens. We also take into account the evolution of these pathogens in response to fertilization scenarios. This allows us to study the sustainability of agricultural practices that contribute to the regulation of epidemics. To answer these questions, we adopted a modelling approach that simulates the effect of different fertilization scenarios. The starting point and originality of our approach was to consider the pathosystem as a consumer-resource system and to use concepts of evolutionary ecology to answer the abovementioned agronomic questions. In the two models developed in this thesis, fertilization directly determines the quantity of resources available for the pathogen. We focus on one of the pathogen's life history traits, the latent period (time period between infection and the onset of sporulating lesions), which corresponds to the minimum duration of an infectious cycle and constrains the pathogen's resource allocation strategy. The latent period determines the amount of resource that will be allocated to either growth of mycelium (and therefore to pathogen size at maturity) or to sporulation (proportional to the pathogen’s size). The models we developed make it possible to study the epidemiological and evolutionary responses of fungal foliar pathogens to crop fertilization. We parameterized our models according to our biological knowledge of the wheat-rust pathosystem. Our modelling work encompasses different spatial and temporal scales: from the lesion where the pathogen feeds directly on its host, to the field and the landscape where the spores that flow between fields are the source of epidemics in the agroecosystem. The first model, at the intersection of the "SEIR" epidemiological models and structured population models, covers the scales of a lesion, the crop canopy and the field. The second model, at the intersection of SEIR and spatial landscape epidemiology models, covers the scales of the field and the agricultural landscape. We study epidemiological and evolutionary dynamics of pathogen populations by comparing empirical and invasion fitness concepts. We show that crop fertilization, by determining the dynamics of available resources for pathogens, has a strong impact on foliar fungal epidemics. Our models predict that pathogen latent period evolves in response to various ecological trade-offs; on the one hand to optimize resources allocation at the leaf scale, on the other hand to win the race against canopy growth. By changing the leaf metabolite content and the rate of canopy growth, fertilization therefore impacts both epidemics and evolutionary responses of pathogen latent period. At the landscape scale, the introduction of various fertilization practices in a previously homogeneous landscape could help to partially regulate epidemics. However, our model predicts that the beneficial effects of heterogeneity will vanish due to the evolution and diversification of pathogens in heterogeneous landscapes. This work sets the stage for further work on the effect and sustainability of agricultural practices on the regulation of crop epidemics in agroecosystems. Finally, by performing a meta-analysis, we bring out a strong relation between pathogen trophic type and latent period, suggesting that different trophic types of pathogens will respond differently to decreasing fertilization scenarios
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Hantsch, Lydia [Verfasser], Helge [Akademischer Betreuer] Bruelheide, Uwe [Akademischer Betreuer] Braun, and Christopher C. [Akademischer Betreuer] Mundt. "Tree diversity effects on species richness and infestation of foliar fungal pathogens in European tree diversity experiments / Lydia Hantsch. Betreuer: Helge Bruelheide ; Uwe Braun ; Christopher C. Mundt." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2013. http://d-nb.info/1046563483/34.
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Bernard, Frédéric. "Le développement des champignons pathogènes foliaires répond à la température, mais à quelle température ?" Phd thesis, AgroParisTech, 2012. http://pastel.archives-ouvertes.fr/pastel-00909360.
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La température est un des principaux facteurs climatiques pilotant le développement des champignons pathogènes foliaires pendant les différentes étapes de leur cycle parasitaire. Puisque ces microorganismes se développent à la surface, puis à l'intérieur des feuilles, c'est la température de feuille (" body temperature " en écologie) qui pilote leur développement. En épidémiologie végétale, c'est toutefois la température d'air qui est utilisée pour caractériser l'effet de la température sur le développement des agents pathogènes foliaires. Or, la température de feuille peut différer significativement de la température d'air en fonction des conditions climatiques. La prise en compte de la température d'air pour étudier la dynamique des maladies foliaires ne peut donc s'affranchir de deux biais : la température mesurée n'est pas celle qui est réellement perçue par l'agent pathogène et l'hétérogénéité spatiale des températures au sein du peuplement n'est pas prise en compte. De plus, la relation entre la température et le développement des agents pathogènes est non linéaire, ce qui limite la gamme de validité autorisant l'utilisation des sommes de températures, pourtant largement employées en protestion des cultures. L'objectif général de cette thèse est de reconsidérer la prise en compte de la température pour l'étude du développement des champignons pathogènes foliaires.Le pathosystème blé-Mycosphaerella graminicola a été choisi en tant qu'objet d'étude. La stratégie adoptée pour atteindre les objectifs de la thèse combine deux approches complémentaires, l'expérimentation et la modélisation. Pour la première fois, la loi de réponse d'un agent pathogène foliaire à la température de feuille a été établie. Un dispositif expérimental innovant a permis d'établir la loi de réponse pour trois isolats sur une large gamme de températures foliaires, via la mesure en continu de la température de 191 feuilles (F et F) inoculées et l'utilisation d'un système de forçage thermique par lampe infrarouge. La loi de réponse de la période de latence de la septoriose à la température de feuille s'apparente au concept de courbe de performance thermique développé en écologie. Celle-ci étant non linéaire sur l'ensemble de la gamme de température étudiée, l'impact de l'amplitude de fluctuations de température de feuille a été caractérisé. Une amplitude élévée a conduit à plusieurs effets négatifs pour le développement de M. graminicola : l'augmentation de la durée du cycle de l'agent pathogène, la diminution de la surface sporulante des lésions et de la densité de pycnides. Les différences de cinétique de développement en fonction de l'amplitude des fluctuations ne sont que partiellement expliquées par l'effet Kaufmann (purement mathématiques), suggérant que M. graminicola atténue les conséquences négatives d'amplitudes de fluctuation plus élevées. Enfin, les simulations du développement de la septoriose réalisées à partir de données de températures foliaires diffèrent signicativement de celles réalisées à partir de températures d'air mesurées de façon standard par une station météorologique. Ces simulations ont également souligné le caractère déterminant du pas de temps considéré.Par le transfert de concepts d'écologie vers l'épidémiologie, cette thèse ouvre des pistes pour améliorer la prise en compte de la température dans les modèles épidémiologiques. Elle contribue au développement d'une meilleure compréhension des mécanismes par lesquels l'environnement affecte les microorganismes, point clé pour le développement de modèles mécanistes de réponses possibles au changement climatique
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Noronha, Marissônia de Araujo. "Escala diagramática para avaliação da mancha preta em folhas de citros e efeito da temperatura e da duração do molhamento na pré-penetração de conídios de Guignardia citricarpa Kiely [Phyllosticta citricarpa (McAlp.) Van der Aa]." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11135/tde-21032003-133754/.
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A mancha preta dos citros causada pelo fungo Guignardia citricarpa Kiely [Phyllosticta citricarpa (McAlp.) Van der Aa], possui duas formas de infecção, conídios e ascósporos. Informações a respeito da importância dos conídios na epidemiologia da doença são escassas ou controversas. Visando uma maior compreensão sobre o patossistema citros-G. citricarpa (P. citricarpa), os objetivos desta dissertação foram: elaborar e validar uma escala diagramática para avaliação da severidade da mancha preta em folhas de citros; verificar o efeito da temperatura e da duração do período de molhamento na formação de apressórios formados a partir de conídios; observar por meio de microscopia eletrônica de varredura a germinação de conídios e a formação de apressórios sobre folhas destacadas de limão 'Siciliano' submetidas a diferentes temperaturas e períodos de molhamento. A escala diagramática com níveis de severidade de 1; 3; 6; 12; e 24% de área foliar lesionada foi validada por dois grupos de avaliadores, com e sem experiência na quantificação de doenças. Comparada com a avaliação sem escala, o uso da escala proporcionou melhor precisão e acurácia tanto para avaliadores experientes como inexperientes, quando considerada a estimativa média dos mesmos. Na maioria dos casos, os desvios entre estimativas e severidade atual da doença foram mais evidentes para os níveis de severidade entre 5 e 15%. A reprodutibilidade das avaliações resultou em valores de R 2 mais uniformes para a maioria dos avaliadores experientes. Diferenças consideráveis de precisão foram observadas entre avaliadores inexperientes. O efeito da temperatura (10 o C 40 o C) e da duração do molhamento (4 48 h) na formação de apressórios formados a partir de conídios de G. citricarpa (P. citricarpa) foi avaliado sob condições "in vitro" e sobre a superfície de folhas de limão 'Siciliano'. A formação de apressórios ocorreu em todas as temperaturas a partir de 12 horas de molhamento, sendo os extremos de temperatura (10 o C e 40 o C) menos favoráveis à formação de apressórios. A temperatura mínima para formação de apressórios, estimada pela função beta generalizada foi de 3 o C e a máxima de 48,4 o C, ambas para 48 horas de molhamento. A formação de apressórios foi consideravelmente favorecida pela duração do período de molhamento, com o máximo de apressórios formados a 24 horas de molhamento, para a maioria das temperaturas. O período de molhamento constituído de 48 horas foi essencial para que os esporos submetidos a temperaturas de 10 o C e 40 o C, formassem apressórios. A superfície de resposta obtida pela multiplicação das funções beta generalizada e monomolecular apresentou um ajuste satisfatório para os dados observados na estimativa da porcentagem relativa de apressórios formados (R 2 =0,75). As amostras observadas em microscopia eletrônica de varredura possibilitaram a aquisição de imagens de conídios e apressórios sobre a superfície de folhas de limão 'Siciliano' em todas as combinações de temperatura e molhamento avaliadas.Citrus black spot caused by Guignardia citricarpa Kiely [Phyllosticta citricarpa (McAlp.) van der Aa] presents two infection forms, conidia and ascospores. Information regarding the importance of the conidia in the epidemiology of the disease is scarce and controversial. Seeking a better understanding on the pathosystem citrus-G. citricarpa (P. citricarpa), the objectives of this dissertation were: elaborate and validate a diagrammatic scale for assessments of the citrus black spot; verify the effect of the temperature and of the wetness duration in the appressorium formation; observe through scanning electron microscopy the germination and formation of appressorium on outstanding lemon 'Siciliano' leaves submitted to different temperatures and wetness duration. The diagrammatic scale with severity levels of 1; 3; 6; 12; and 24% of diseased leaf area was validated by two groups of raters, with experience and without experience in the quantification of diseases. The scale provided better precision and accuracy for both experienced and inexperienced raters, considering the estimates average of them. In the majority of cases, the bias between estimated and actual disease severity were more evident for disease severity levels between 5 and 15%. The reproducibility of assessments resulted in R 2 with more uniforms values for the majority of the experienced raters, considerable differences of precision were observed among inexperienced raters. The effect of the temperature (10 o C - 40 o C) and of the wetness duration (4 48 h) in the germination of conidia and appressoria formation of G. citricarpa (P. citricarpa), was assessed "in vitro" and on the surface of lemon 'Siciliano' leaves. The appressoria formation occurred in all the temperatures starting from 12 hours of wetness. The extreme temperatures (10 o C and 40 o C) were less favorable to the apressorium formation. The minimum temperature for appressorium formation, estimated by generalized beta function was of 3 o C and the maximum of 48,4 o C, both for 48 hours of wetness. The appressorium formation was favored considerably by the wetness duration period, with the maximum of apressoria formed at 24 hours of wetness, for majority of the temperatures. The wetness duration period constituted of 48 hours was essential so that the spores submitted to temperatures of 10 o C and 40 o C, formed appressorium. The response surface obtained by the multiplication of the generalized beta and monomolecular functions provided a close fit to observed data in the estimate of the relative percentage of formed appressorium (R 2 =0,75). The samples observed in scanning electron microscopy made possible the acquisition of images of conidia and appressoria on the surface of lemon 'Siciliano' leaves in all the temperature combinations and wetness evaluated.
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Boaretto, Luis Felipe. "Identificação de proteínas diferencialmente expressas e avaliação da composição química da parede celular de folha de clones de Eucalyptus grandis em resposta à ferrugem (Puccinia psidii Winter)." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-14072008-175231/.
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O Eucalyptus é o gênero mais importante para a indústria brasileira de papel e celulose. Eucalyptus grandis Hill ex. Maiden e seus híbridos são preferencialmente usados pela indústria devido ao rápido crescimento e alta produtividade volumétrica. Embora possua características adequadas à utilização comercial, vários estresses abióticos e bióticos influenciam sua produção. O IPGRI (International Plant Genetic Resources Institute) destaca a Puccinia psidii como sendo a maior ameaça para a cultura nos tempos atuais. A doença não co-evoluiu com o hospedeiro e por essa razão, torna o patógeno um elemento potencial a vencer as barreiras impostas pelo hospedeiro. O fungo ataca plantas jovens, incluindo mudas em viveiros, plantas em jardins clonais e plantações comercias com até 2 anos de idade. Com o objetivo de identificar proteínas diferencialmente expressas e avaliar as mudanças ocorridas na composição química da parede celular das folhas, o presente trabalho analisou o impacto da presença do fungo sobre os clones comerciais, resistentes (7) e suscetíveis (24), de eucalipto. Os clones de E. grandis, 7 e 24, previamente inoculados com uredósporos de P. psidii, foram utilizados para extração de proteínas após 24 horas de interação com o fungo. As análises foram realizadas com auxílio de SDS-PAGE de primeira e segunda dimensão, em gradiente de pH na faixa de 4-7, utilizando-se 750 µg de proteínas. As imagens dos géis, em triplicata, analisadas pelo programa (Image Master Elite v. 3.01), possibilitaram a identificação de 466 spots. A comparação entre os perfis eletroforéticos dos clones que foram analisados e os controles não inoculados, mostrou que o processo de infecção do fungo nas plantas induziu o aparecimento de 72 spots exclusivos para o clone 7 além de alterações do volume de outros 115 spots. Já para o clone 24, a exposição ao fungo promoveu o aparecimento de 22 spots exclusivos e alterações de outros 98. Os perfis eletroforéticos dos clones controle, que não foram expostos ao fungo, mostraram diferenças genéticas entre os clones 7 e 24. O clone resistente, apresentou grande concentração de spots na região entre 14 a 45 kDa. Já para o clone suscetível, os spots se concentraram na região entre 25 a 97 kDa. A avaliação do conteúdo de carboidratos e ácidos urônicos da parede celular mostrou alterações no conteúdo dos açúcares no material inoculado com P. psidii, após 24 horas, 6 e 12 dias de inoculação. Os teores de glicose observados para os clones 7 e 24, já após 24 horas da inoculação, mostraram-se bastante alterados, indicando que esse açúcar possui papel chave no processo de formação da parede celular e conseqüentemente no mecanismo de defesa vegetal.Eucalyptus is the most important genus for the Brazilian pulp and paper industry. Eucalyptus grandis Hill ex. Maiden and hybrids are preferentially used by the industry due to its rapid growth and high volumetric productivity. Although they possess characteristics adequate for commercial use, various biotic and abiotic stresses influence production. IPGRI (International Plant Genetic Resources Institute) highlight Puccinia psidii as the largest current threat to the culture. The disease did not co-evolve with the host and for this reason has become the pathogen with most potential to overcome the barriers imposed by the host. The fungus attacks young plants, including saplings in nursery, clonal gardens and commercial plants up to 2 years-old. With the objectives of identifying the proteins differentially expressed and evaluate the changes occurring in the chemical composition of the cell walls in the leaves, the present work analyzed the impact of the presence of the fungus on the commercial eucalyptus clones, resistant (7) and susceptible (24). The E. grandis clones (7 and 24) were inoculated with P. psidii urideospores and proteins extracted after 24 hours interaction with the fungus. The analyses were carried out using a pH gradient (4-7) in the first and SDS-PAGE in the second dimension, loading 750 µg onto the gel. The gel images, in triplicate, were analyzed using the software Image Master Elite v. 3.01, allowing the identification of 466 spots. The electrophoretic profiles for each clone were analyzed and compared to the uninoculated controls, showing that the fungal infection process induced the appearance of 72 exclusive spots in clone 7 and an alteration in the volume of another 115 spots. In clone 24, exposure to the fungus induced the appearance of 22 exclusive spots and altered another 98. The electrophoretic profiles of the control clone, not exposed to the fungus, demonstrated genetic differences between the 7 and 24. The resistant clone (7) presented a large concentration of spots around 14 to 45 kDa. In contrast, the susceptible clone (24) presented a concentration of spots around 25 to 97 kDa. Evaluation of the carbohydrate and uronic acid content of the cell wall showed an alteration in the sugar content in the material exposed to P. psidii after 24 hour, 6 and 12 days after inoculation. The glucose levels observed for clones 7 and 24 were considerable altered 24 hours after inoculation, indicating that this sugar has a key role in cell wall formation and consequently in the plant defense mechanism.
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Ingram, Russell J., and Foster Levy. "Identity and Symptomatology of a Newly Described Lily Leaf Spot Disease (Pseudocercosporella Inconspicua) of Gray’s Lily (Lilium Grayi)." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/7786.
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Lily leaf spot is an emerging disease of the globally rare Lilium grayi S. Wats., a species endemic to the southern Appalachian Blue Ridge, USA. The species is considered Threatened or Endangered in the three states where it naturally occurs (North Carolina, Tennessee, Virginia). Disease leads to premature senescence of aboveground tissues and curtailment of sexual reproduction. Spore morphology, completion of Koch’s postulates, and DNA sequence data showed the causative agent of lily leaf spot to be Pseudocercosporella inconspicua (G. Winter) U. Braun, a Lilium-specific basidiomycete. Diagnostic disease symptomatology includes amphigenous necrotic lesions with tan to green margins encircling a white to grey powdery mass of conidia. Studies conducted in the field at Roan Mountain, NC/TN, in the largest known population, showed that a visual disease diagnosis based on morphology can be highly accurate in predicting P. inconspicua infection, and that high concentrations of conidia of P. inconspicua are strongly associated with infected L. grayi, but are largely absent or few on uninfected L. grayi and other species. Field inoculation trials using infected L. grayi leaf tissue as inocula resulted in transmission of disease and induction of premature senescence under natural conditions.
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"FUNCTIONAL DIVERSITY OF FUNGI ASSOCIATED WITH DURUM WHEAT ROOTS IN DIFFERENT CROPPING SYSTEMS." Thesis, 2013. http://hdl.handle.net/10388/ETD-2013-06-1123.
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Differences in pea (Pisum sativum L.) and chickpea (Cicer arietinum L.) microbial compatibility and/ or their associated farming practices may influence root fungi of the following crop and affect the yield. The main objective of this research was to explain the difference in durum wheat (Triticum turgidum L.) yield the year after pea and chickpea crops through changes in the functional diversity of wheat root fungi. The effect of fungicides used on chickpea on the root fungi of a following durum wheat crop was studied using plate culture and pyrosequencing. Pyrosequencing detected more Fusarium spp. in the roots of durum wheat after fungicide-treated chickpea than in non-fungicide treated chickpea. Plate culture revealed that the functional groups of fungi responded differently to fungicide use in the field but the effect on total community was non-significant. Highly virulent pathogens were not affected, but antagonists were suppressed. More fungal antagonists were detected after the chickpea CDC Luna than CDC Vanguard. Fungal species responded differently to the use of fungicides in vitro, but the aggregate inhibition effect on antagonists and highly virulent pathogens was similar.
The effect of chickpea vs. pea previous crop and different chickpea termination times on root fungi of a following durum wheat crop was studied. The abundance of Fusarium spp. increased after cultivation of both cultivars of chickpea as compared to pea according to pyrosequencing and was negatively correlated with durum yield. Plate culture analysis revealed that fungal antagonists were more prevalent after pea than both cultivars of chickpea and chickpea CDC Vanguard increased the abundance of highly virulent pathogens. The abundance of highly virulent pathogens in durum wheat roots was negatively correlated to durum yield. Early termination of chickpea did not change the community of culturable fungi in the roots of a following durum crop.
It is noteworthy that Fusarium redolens was identified for the first time in Saskatchewan and its pathogenicity was confirmed on durum wheat, pea and chickpea. The classical method of root disease diagnostics in cereals is based on the examination of the subcrown internode. I evaluated the method by comparing the fungal communities associated with different subterranean organs of durum wheat. The fungal community of the subcrown internode was different from that of roots and crown, suggesting cautious use of this method.
Books on the topic "Foliar fungal pathogens"
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Keane, PJ, GA Kile, FD Podger, and BN Brown, eds. Diseases and Pathogens of Eucalypts. CSIRO Publishing, 2000. http://dx.doi.org/10.1071/9780643090125.
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Over the last fifty years, there has been an increasing recognition that eucalypts are vulnerable to a wide range of diseases. They have suffered destructive epidemics, particularly of dieback caused by the cinnamon fungus in native forests, of foliar diseases and cankers in plantations, and of dieback of remnant trees on agricultural and grazing land.
This has stimulated intensive research into the causes and management of diseases of the eucalypts. This work represents a comprehensive review of our current knowledge of the health and diseases of eucalypts.
Book chapters on the topic "Foliar fungal pathogens"
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McCartney, H. A., and B. D. L. Fitt. "Dispersal of foliar fungal plant pathogens: mechanisms, gradients and spatial patterns." In The Epidemiology of Plant Diseases, 138–60. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-017-3302-1_7.
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Cassells, Alan C., and Susan M. Rafferty-McArdle. "Priming of Plant Defences by PGPR against Fungal and Bacterial Plant Foliar Pathogens." In Bacteria in Agrobiology: Stress Management, 1–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-662-45795-5_1.
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Kashyap, Priyakshi, Indrani Sharma, Sampurna Kashyap, and Niraj Agarwala. "Arbuscular Mycorrhizal Fungi (AMF)-Mediated Control of Foliar Fungal Diseases." In Arbuscular Mycorrhizal Fungi and Higher Plants, 193–223. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8220-2_9.
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AbstractPlants witness a variety of disease incidences throughout their life, ultimately resulting in reduced plant growth and productivity. Climate change or human interventions have aggravated the incidences of various plant diseases, among which foliar fungal diseases are serious threats. Arbuscular mycorrhizal fungi (AMF) are a mutualistic group of organisms that play a significant role in enhancing plant growth and resilience under varied environmental circumstances. Moreover, it is well established that AMF confers tolerance against several foliar fungal diseases. This chapter highlights how fungal foliar diseases affect plant health and the various roles of AMF in providing resistance to different crop plants. In addition, AMF-mediated alterations in the root system architecture (RSA), modulation of reactive oxygen species (ROS), and reinforcement of the physical barrier that prevents pathogen invasion and establishment have been discussed in detail. Furthermore, the intricate cross talk between AMF and phytohormones or plant metabolites has also been explored. Overall, harnessing the potential of AMF in imparting tolerance against foliar fungal diseases might reduce the reliance on chemical fungicides, thereby introducing an environment-friendly approach for plant protection.
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Ulrich, Danielle E. M., Steve Voelker, J. Renée Brooks, and Frederick C. Meinzer. "Insect and Pathogen Influences on Tree-Ring Stable Isotopes." In Stable Isotopes in Tree Rings, 711–36. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_25.
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AbstractUnderstanding long-term insect and pathogen effects on host tree physiology can help forest managers respond to insect and pathogen outbreaks, and understand when insect and pathogen effects on tree physiology will be exacerbated by climate change. Leaf-level physiological processes modify the carbon (C) and oxygen (O) stable isotopic composition of elements taken up from the environment, and these modifications are recorded in tree-rings (see Chaps. 10.1007/978-3-030-92698-4_9, 10.1007/978-3-030-92698-4_10, 10.1007/978-3-030-92698-4_16 and 10.1007/978-3-030-92698-4_17). Therefore, tree-ring stable isotopes are affected by both the tree’s environment and the tree’s physiological responses to the environment, including insects and pathogens. Tree-ring stable isotopes provide unique insights into the long-term effects of insects and pathogens on host tree physiology. However, insect and pathogen impacts on tree-ring stable isotopes are often overlooked, yet can substantially alter interpretations of tree-ring stable isotopes for reconstructions of climate and physiology. In this chapter, we discuss (1) the effects of insects(defoliators, wood-boring, leaf-feeding), pests (parasitic plants), and pathogens(root and foliar fungi) on hostphysiology (growth, hormonal regulation, gas exchange, water relations, and carbon and nutrient use) as they relate to signals possibly recorded by C and O stable isotopes in tree-rings, (2) how tree-ring stable isotopes reveal insect and pathogen impacts and the interacting effects of pathogens and climate on hostphysiology, and (3) the importance of considering insect and pathogen impacts for interpreting tree-ring stable isotopes to reconstruct past climate or physiology.
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"Bad Moon Rising." In Good Enough to Eat? Next Generation GM Crops, 121–56. The Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/bk9781788010856-00121.
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In the early 1990s, with my plant pathologist colleague, Liz Aitken, we attempted to convince the Australian banana industry that it was an essential long-term strategy for them to invest in banana genetic improvement. The local industry (like most others around the world) was based almost entirely on a single cultivar, the Cavendish banana. If you know your bananas, you will also know that the Cavendish, while a worthy workhorse, is not exactly the most flavoursome banana around. In addition to that, Cavendish bananas are vulnerable to some pretty savage fungal pathogens, including a couple of foliar pathogens known as yellow Sigatoka, and black Sigatoka, after the Sigatoka Valley in Fiji where they were first recorded. These pathogens are pretty lame though, because while they are economically troublesome, they can be controlled by regular application of fungicides and sanitation measures. This however is not the case with the biggest threat to banana production worldwide.
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Bahadur, Amar, and Pranab Dutta. "Trchoderma Spp.: Their Impact in Crops Diseases Management." In Trichoderma [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.101846.
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Trichoderma species, a cosmopolitan fungi, present in all types of soil, manure, and decaying plant tissues that can degrade domestic waste relatively quickly without emitting bad odors. Trichoderma is recognized worldwide as potential fungal bio-control agents for the management of various foliar and soil-borne plant pathogens, highly compatible with sustainable agriculture and play major role as a component of integrated pest management. Bio-control agents are an antagonism and eco-friendly approach for managing plant diseases. Trichoderma as bioagent area effective not only against soil-borne plant pathogens, but also against nematodes without any adverse effect on beneficial microbes. Trichoderma is capable of growth promotions in crops. There are two major mass production methods of Trichoderma spp. viz., solid state fermentation and liquid state fermentation. In solid, fungus is grown on various cereal grains, agricultural wastes, and byproducts, and these products are used mainly for direct soil application to suppress the soil-borne inoculums. In a liquid state, Trichoderma is grown on media such as molasses and yeast in deep tanks and fermentation can be made into different formulations such as dusts, granules, pellets, wettable powders. As seed-treating agents or bio-priming agents, Trichoderma formulations can be successfully used against several soil-borne diseases caused by Pythium, Phytophthora, Rhizoctonia, Fusarium and Sclerotium, spp. in several crops.
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Gilbert, Gregory S., and Ingrid M. Parker. "Types of plant diseases." In The Evolutionary Ecology of Plant Disease, 83–96. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198797876.003.0008.
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Abstract Plant pathogens affect their hosts in diverse ways. Some deprive the host of carbon by parasitizing it or by reducing photosynthetic tissue, and some restrict access to water by disrupting the vascular system; either can slow the growth of the plant and reduce host fecundity. Other pathogens directly kill parts or all of the plant, and still other pathogens change growth patterns by manipulating host physiology or genetics. All plants can experience foliar diseases, developmental diseases caused by hormonal manipulation by the pathogen, stunting or dwarfing, damping off, vascular diseases, and root rot. Diseases of woody plant species include cankers and heart rot/butt rot. Some pathogens attack flowers and the reproductive organs of plants, including smut fungi on the anthers of flowers, fruit rot, and seed-decay fungi. All these impacts can reduce the fitness of the plants, altering population dynamics or driving down crop yields. Necrotrophs actively kill cells, causing chlorosis and necrosis, while biotrophs like rusts and viruses depend on live plant tissue to grow and reproduce. The life-history strategies of the pathogens, whether necrotrophs, biotrophs, or opportunistic saprotrophs, often strongly influence the impacts they have on their hosts as well as their level of host specificity.
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Chaliha, Chayanika, and Eeshan Kalita. "Blister Blight Disease of Tea: An Enigma." In Diagnostics of Plant Diseases [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95362.
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Tea is one of the most popular beverages consumed across the world and is also considered a major cash crop in countries with a moderately hot and humid climate. Tea is produced from the leaves of woody, perennial, and monoculture crop tea plants. The tea leaves being the source of production the foliar diseases which may be caused by a variety of bacteria, fungi, and other pests have serious impacts on production. The blister blight disease is one such serious foliar tea disease caused by the obligate biotrophic fungus Exobasidium vexans. E. vexans, belonging to the phylum basidiomycete primarily infects the young succulent harvestable tea leaves and results in ~40% yield crop loss. It reportedly alters the critical biochemical characteristics of tea such as catechin, flavonoid, phenol, as well as the aroma in severely affected plants. The disease is managed, so far, by administering high doses of copper-based chemical fungicides. Although alternate approaches such as the use of biocontrol agents, biotic and abiotic elicitors for inducing systemic acquired resistance, and transgenic resistant varieties have been tested, they are far from being adopted worldwide. As the research on blister blight disease is chiefly focussed towards the evaluation of defense responses in tea plants, during infection very little is yet known about the pathogenesis and the factors contributing to the disease. The purpose of this chapter is to explore blister blight disease and to highlight the current challenges involved in understanding the pathogen and pathogenic mechanism that could significantly contribute to better disease management.
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Chaliha, Chayanika, and Eeshan Kalita. "Blister Blight Disease of Tea: An Enigma." In Diagnostics of Plant Diseases [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95362.
Full textAbstract:
Tea is one of the most popular beverages consumed across the world and is also considered a major cash crop in countries with a moderately hot and humid climate. Tea is produced from the leaves of woody, perennial, and monoculture crop tea plants. The tea leaves being the source of production the foliar diseases which may be caused by a variety of bacteria, fungi, and other pests have serious impacts on production. The blister blight disease is one such serious foliar tea disease caused by the obligate biotrophic fungus Exobasidium vexans. E. vexans, belonging to the phylum basidiomycete primarily infects the young succulent harvestable tea leaves and results in ~40% yield crop loss. It reportedly alters the critical biochemical characteristics of tea such as catechin, flavonoid, phenol, as well as the aroma in severely affected plants. The disease is managed, so far, by administering high doses of copper-based chemical fungicides. Although alternate approaches such as the use of biocontrol agents, biotic and abiotic elicitors for inducing systemic acquired resistance, and transgenic resistant varieties have been tested, they are far from being adopted worldwide. As the research on blister blight disease is chiefly focussed towards the evaluation of defense responses in tea plants, during infection very little is yet known about the pathogenesis and the factors contributing to the disease. The purpose of this chapter is to explore blister blight disease and to highlight the current challenges involved in understanding the pathogen and pathogenic mechanism that could significantly contribute to better disease management.
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Ghareeb, Rehab Yassin, Yara Yassin, and Nader R. Abdelsalam. "Overview of Plant Nematodes." In Advances in Environmental Engineering and Green Technologies, 1–13. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-8083-0.ch001.
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Nematodes are multicellular organisms that may shed their cuticle. The Ecdysozoa category of organisms usually are tiny and subterranean. Nowadays, plant parasitic nematodes are known as the main agricultural pathogens and are recognized to attack plants and propose crop yield damage over the world. Some assessments suggest they cause over 70 billion dollars of losses worldwide each year. Nematodes are soil-borne (with exceptions like Aphelenchoides, a foliar nematode). Even though many saprophytic nematodes are embedded in soils, they vary from plant pathogenic nematodes in that the last have stylets. Soil nematodes, exceptionally the nematodes feeding on bacteria and fungi, can help to maintain sufficient levels of plant-available nitrogen in farming. Plant-parasitic nematodes are costly losses in crop yield production. Ubiquitous in nature, phyto-parasitic nematodes are specific to every important agricultural crop and reveal a significant restriction on global food security.
Conference papers on the topic "Foliar fungal pathogens"
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Filipovics, Maksims. "Hyperspectral imaging for early detection of foliar fungal diseases on small grain cereals: a minireview." In Research for Rural Development 2023 : annual 29th international scientific conference proceedings. Latvia University of Life Sciences and Technologies, 2023. http://dx.doi.org/10.22616/rrd.29.2023.001.
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Foliar fungal diseases of small grain cereals are economically among the most important diseases worldwide and in the Baltics. Finding an effective, reliable, and easily accessible method for plant disease diagnosis still presents a challenge. Currently used methods include visual examination of the affected plant, morphological characterization of isolated pathogens and different molecular, and serological methods. All of these methods have important limitations, especially for large-area applications. Hyperspectral imaging is a promising technique to assess fungal diseases of plants, as it is a non-invasive, indirect detection method, where the plant’s responses to the biotic stress are identified as an indicator of the disease. Hyperspectral measurements can reveal a relationship between the spectral reflectance properties of plants and their structural characteristics, pigment concentrations, water level, etc., which are considerably influenced by biotic plant stress. Despite the high accuracy of the information obtained from hyperspectral detectors, the interpretation is still problematic, as it is influenced by various circumstances: noise level, lighting conditions, abiotic stress level, a complex interaction of the genotype and the environment, etc. The application of hyperspectral imaging in everyday farming practice will potentially allow farmers to obtain timely and precise information about the development of diseases and affected areas. This review provides an introduction into issues of hyperspectral imaging and data analysis and explores the published reports of worldwide research on the use of hyperspectral analysis in the detection of foliar fungal diseases of small-grain cereals.
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Стратулат, Татьяна, Татьяна Щербакова, Штефан Кручан, and Андрей Лунгу. "Пораженность листвы древесных насаждений города Кишинева комплексом гнилей летом 2021 года." In VIIth International Scientific Conference “Genetics, Physiology and Plant Breeding”. Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2021. http://dx.doi.org/10.53040/gppb7.2021.92.
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To determine the complex of fungi that cause rot on the leaves and needles of tree species in the green spaces of Chisinau, foliage was collected in four sectors of the city. It was determined by microbio-logical methods that the complex of pathogens on the leaves differs little in different sectors. The main leaf rot fungi present on the affected leaves and needles are Alternaria sp., Aspergillus sp., Fusarium sp., Penicillium sp. For the treatment of the green spaces of Chisinau against diseases, it is advisable to carry out phytosanitary measures with biological products.
Reports on the topic "Foliar fungal pathogens"
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Harms, Nathan, Judy Shearer, James Cronin, and John Gaskin. Geographic and genetic variation in susceptibility of Butomus umbellatus to foliar fungal pathogens. Engineer Research and Development Center (U.S.), August 2021. http://dx.doi.org/10.21079/11681/41662.
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Large-scale patterns of plant invasions may reflect regional heterogeneity in biotic and abiotic factors and genetic variation within and between invading populations. Having information on how effects of biotic resistance vary spatially can be especially important when implementing biological control because introduced agents may have different Impacts through interactions with host-plant genotype, local environment, or other novel enemies. We conducted a series of field surveys and laboratory studies to determine whether there was evidence of biotic resistance, as foliar fungal pathogens, in two introduced genotypes (triploid G1, diploid G4) of the Eurasian wetland weed, Butomus umbellatus L. in the USA. We tested whether genotypes differed in disease attack and whether spatial patterns in disease incidence were related to geographic location or climate for either genotype. After accounting for location (latitude, climate), G1 plants had lower disease incidence than G4 plants in the field (38% vs. 70%) but similar pathogen richness. In contrast, bioassays revealed G1 plants consistently received a higher damage score and had larger leaf lesions regardless of pathogen. These results demonstrate that two widespread B. umbellatus genotypes exhibit different susceptibility to pathogens and effectiveness of pathogen biological controls may depend on local conditions.
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Harman, Gary E., and Ilan Chet. Enhancement of plant disease resistance and productivity through use of root symbiotic fungi. United States Department of Agriculture, July 2008. http://dx.doi.org/10.32747/2008.7695588.bard.
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The objectives of the project were to (a) compare effects ofT22 and T-203 on growth promotion and induced resistance of maize inbred line Mol7; (b) follow induced resistance of pathogenesis-related proteins through changes in gene expression with a root and foliar pathogen in the presence or absence of T22 or T-203 and (c) to follow changes in the proteome of Mol? over time in roots and leaves in the presence or absence of T22 or T-203. The research built changes in our concepts regarding the effects of Trichoderma on plants; we hypothesized that there would be major changes in the physiology of plants and these would be reflected in changes in the plant proteome as a consequence of root infection by Trichoderma spp. Further, Trichoderma spp. differ in their effects on plants and these changes are largely a consequence of the production of different elicitors of elicitor mixtures that are produced in the zone of communication that is established by root infection by Trichoderma spp. In this work, we demonstrated that both T22 and T-203 increase growth and induce resistance to pathogens in maize. In Israel, it was shown that a hydrophobin is critical for root colonization by Trichoderma strains, and that peptaibols and an expansin-like protein from Ttrichoderma probably act as elicitors of induced resistance in plants. Further, this fungus induces the jasmonate/ethylene pathway of disease resistance and a specific cucumber MAPK is required for transduction of the resistance signal. This is the first such gene known to be induced by fungal systems. In the USA, extensive proteomic analyses of maize demonstrated a number of proteins are differentially regulated by T. harzianum strain T22. The pattern of up-regulation strongly supports the contention that this fungus induces increases in plant disease resistance, respiratory rates and photosynthesis. These are all very consistent with the observations of effects of the fungus on plants in the greenhouse and field. In addition, the chitinolytic complex of maize was examined. The numbers of maize genes encoding these enzymes was increased about 3-fold and their locations on maize chromosomes determined by sequence identification in specific BAC libraries on the web. One of the chitinolytic enzymes was determined to be a heterodimer between a specific exochitinase and different endochitinases dependent upon tissue differences (shoot or root) and the presence or absence of T. harzianum. These heterodimers, which were discovered in this work, are very strongly antifungal, especially the one from shoots in the presence of the biocontrol fungus. Finally, RNA was isolated from plants at Cornell and sent to Israel for transcriptome assessment using Affymetrix chips (the chips became available for maize at the end of the project). The data was sent back to Cornell for bioinformatic analyses and found, in large sense, to be consistent with the proteomic data. The final assessment of this data is just now possible since the full annotation of the sequences in the maize Affy chips is just now available. This work is already being used to discover more effective strains of Trichoderma. It also is expected to elucidate how we may be able to manipulate and breed plants for greater disease resistance, enhanced growth and yield and similar goals. This will be possible since the changes in gene and protein expression that lead to better plant performance can be elucidated by following changes induced by Trichoderma strains. The work was in, some parts, collaborative but in others, most specifically transcriptome analyses, fully synergistic.
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Reisch, Bruce, Avichai Perl, Julie Kikkert, Ruth Ben-Arie, and Rachel Gollop. Use of Anti-Fungal Gene Synergisms for Improved Foliar and Fruit Disease Tolerance in Transgenic Grapes. United States Department of Agriculture, August 2002. http://dx.doi.org/10.32747/2002.7575292.bard.
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Original objectives . 1. Test anti-fungal gene products for activity against Uncinula necator, Aspergillus niger, Rhizopus stolonifer and Botrytis cinerea. 2. For Agrobacterium transformation, design appropriate vectors with gene combinations. 3. Use biolistic bombardment and Agrobacterium for transformation of important cultivars. 4. Characterize gene expression in transformants, as well as level of powdery mildew and Botrytis resistance in foliage of transformed plants. Background The production of new grape cultivars by conventional breeding is a complex and time-consuming process. Transferring individual traits via single genes into elite cultivars was proposed as a viable strategy, especially for vegetatively propagated crops such as grapevines. The availability of effective genetic transformation procedures, the existence of genes able to reduce pathogen stress, and improved in vitro culture methods for grapes, were combined to serve the objective of this proposal. Effective deployment of resistance genes would reduce production costs and increase crop quality, and several such genes and combinations were used in this project. Progress The efficacy of two-way combinations of Trichoderma endochitinase (CHIT42), synthetic peptide ESF12 and resveratrol upon the control of growth of Botrytis cinerea and Penicillium digitatum were evaluated in vitro. All pairwise interactions were additive but not synergistic. Per objective 2, suitable vectors with important gene combinations for Agrobacterium transformation were designed. In addition, multiple gene co-transformation by particle bombardment was also tested successfully. In New York, transformation work focused on cultivars Chardonnay and Merlot, while the technology in Israel was extended to 41B, R. 110, Prime, Italia, Gamay, Chardonnay and Velika. Transgenic plant production is summarized in the appendix. Among plants developed in Israel, endochitinase expression was assayed via the MuchT assay using material just 1-5 days after co-cultivation. Plants of cv. Sugraone carrying the gene coding for ESF12, a short anti-fungal lytic peptide under the control of the double 358 promoter, were produced. Leaf extracts of two plants showed inhibition zones that developed within 48 h indicating the inhibitory effect of the leaf extracts on the six species of bacteria. X fastidiosa, the causal organism of Pierce's disease, was very sensitive to leaf extracts from ESF12 transformed plants. Further work is needed to verify the agricultural utility of ESF12 transformants. In New York, some transformants were resistant to powdery mildew and Botrytis fruit rot. Major conclusions, solutions, achievements and implications The following scientific achievements resulted from this cooperative BARD project: 1. Development and improvement of embryogenesis and tissue culture manipulation in grape, while extending these procedures to several agriculturally important cultivars both in Israel and USA. 2. Development and improvement of novel transformation procedures while developing transformation techniques for grape and other recalcitrant species. 3. Production of transgenic grapevines, characterization of transformed vines while studying the expression patterns of a marker gene under the control of different promoter as the 35S CaMV in different part of the plants including flowers and fruits. 4. Expression of anti-fungal genes in grape: establishment of transgenic plants and evaluation of gene expression. Development of techniques to insert multiple genes. 5. Isolation of novel grape specific promoter to control the expression of future antimicrobial genes. It is of great importance to report that significant progress was made in not only the development of transgenic grapevines, but also in the evaluation of their potential for increased resistance to disease as compared with the non engineered cultivar. In several cases, increased disease resistance was observed. More research and development is still needed before a product can be commercialized, yet our project lays a framework for further investigations.
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Perl, Avichai, Bruce I. Reisch, and Ofra Lotan. Transgenic Endochitinase Producing Grapevine for the Improvement of Resistance to Powdery Mildew (Uncinula necator). United States Department of Agriculture, January 1994. http://dx.doi.org/10.32747/1994.7568766.bard.
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The original objectives are listed below: 1. Design vectors for constitutive expression of endochitinase from Trichoderma harzianum strain P1. Design vectors with signal peptides to target gene expression. 2. Extend transformation/regeneration technology to other cultivars of importance in the U.S. and Israel. 3. Transform cultivars with the endochitinase constructs developed as part of objective 1. A. Characterize foliar powdery mildew resistance in transgenic plants. Background of the topic Conventional breeding of grapevines is a slow and imprecise process. The long generation cycle, large space requirements and poor understanding of grapevine genetics prevent rapid progress. There remains great need to improve existing important cultivars without the loss of identity that follows from hybridization. Powdery mildew (Uncinula necator) is the most important fungal pathogen of grapevines, causing economic losses around the world. Genetic control of powdery mildew would reduce the requirement for chemical or cultural control of the disease. Yet, since the trait is under polygenic control, it is difficult to manipulate through hybridization and breeding. Also, because grapevines are heterozygous and vegetatively propagated cultivar identity is lost in the breeding process. Therefore, there is great need for techniques to produce transgenic versions of established cultivars with heterologous genes conferring disease resistance. Such a gene is now available for control of powdery mildew of grapevines. The protein coded by the Endochitinase gene, derived from Trichoderma harzianum, is very effective in suppressing U. necator growth. The goal of this proposal is to develop transgenic grapevines with this antifungal gene, and to test the effect of this gene on resistance to powdery mildew. Conclusions, achievements and implications Gene transfer technology for grape was developed using commercial cultivars for both wine and table grapes. It paved the way for a new tool in grapevine genetic studies enabling the alteration of specific important traits while maintaining the essential features of existing elite cultivars. Regeneration and transformation technologies were developed and are currently at an advanced stage for USA wine and Israeli seedless cultivars, representing the cutting edge of grape genetic engineering studies worldwide. Transgenic plants produced are tested for powdery mildew resistance in greenhouse and field experiments at both locations. It is our ultimate goal to develop transgenic grapes which will be more efficient and economical for growers to produce, while also providing consumers with familiar products grown with reduced chemical inputs.